From: Davide Caratti dcaratti@redhat.com
commit e70f7a11876a1a788ceadf75e9e5f7af2c868680 upstream.
the following script:
# tc qdisc add dev eth0 handle 0x1 root fq_pie flows 2 # tc qdisc add dev eth0 clsact # tc filter add dev eth0 egress matchall action skbedit priority 0x10002 # ping 192.0.2.2 -I eth0 -c2 -w1 -q
produces the following splat:
BUG: KASAN: slab-out-of-bounds in fq_pie_qdisc_enqueue+0x1314/0x19d0 [sch_fq_pie] Read of size 4 at addr ffff888171306924 by task ping/942
CPU: 3 PID: 942 Comm: ping Not tainted 5.12.0+ #441 Hardware name: Red Hat KVM, BIOS 1.11.1-4.module+el8.1.0+4066+0f1aadab 04/01/2014 Call Trace: dump_stack+0x92/0xc1 print_address_description.constprop.7+0x1a/0x150 kasan_report.cold.13+0x7f/0x111 fq_pie_qdisc_enqueue+0x1314/0x19d0 [sch_fq_pie] __dev_queue_xmit+0x1034/0x2b10 ip_finish_output2+0xc62/0x2120 __ip_finish_output+0x553/0xea0 ip_output+0x1ca/0x4d0 ip_send_skb+0x37/0xa0 raw_sendmsg+0x1c4b/0x2d00 sock_sendmsg+0xdb/0x110 __sys_sendto+0x1d7/0x2b0 __x64_sys_sendto+0xdd/0x1b0 do_syscall_64+0x3c/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7fe69735c3eb Code: 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 f3 0f 1e fa 48 8d 05 75 42 2c 00 41 89 ca 8b 00 85 c0 75 14 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 75 c3 0f 1f 40 00 41 57 4d 89 c7 41 56 41 89 RSP: 002b:00007fff06d7fb38 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 000055e961413700 RCX: 00007fe69735c3eb RDX: 0000000000000040 RSI: 000055e961413700 RDI: 0000000000000003 RBP: 0000000000000040 R08: 000055e961410500 R09: 0000000000000010 R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff06d81260 R13: 00007fff06d7fb40 R14: 00007fff06d7fc30 R15: 000055e96140f0a0
Allocated by task 917: kasan_save_stack+0x19/0x40 __kasan_kmalloc+0x7f/0xa0 __kmalloc_node+0x139/0x280 fq_pie_init+0x555/0x8e8 [sch_fq_pie] qdisc_create+0x407/0x11b0 tc_modify_qdisc+0x3c2/0x17e0 rtnetlink_rcv_msg+0x346/0x8e0 netlink_rcv_skb+0x120/0x380 netlink_unicast+0x439/0x630 netlink_sendmsg+0x719/0xbf0 sock_sendmsg+0xe2/0x110 ____sys_sendmsg+0x5ba/0x890 ___sys_sendmsg+0xe9/0x160 __sys_sendmsg+0xd3/0x170 do_syscall_64+0x3c/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae
The buggy address belongs to the object at ffff888171306800 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 36 bytes to the right of 256-byte region [ffff888171306800, ffff888171306900) The buggy address belongs to the page: page:00000000bcfb624e refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x171306 head:00000000bcfb624e order:1 compound_mapcount:0 flags: 0x17ffffc0010200(slab|head|node=0|zone=2|lastcpupid=0x1fffff) raw: 0017ffffc0010200 dead000000000100 dead000000000122 ffff888100042b40 raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff888171306800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888171306880: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
ffff888171306900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^ ffff888171306980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888171306a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
fix fq_pie traffic path to avoid selecting 'q->flows + q->flows_cnt' as a valid flow: it's an address beyond the allocated memory.
Fixes: ec97ecf1ebe4 ("net: sched: add Flow Queue PIE packet scheduler") CC: stable@vger.kernel.org Signed-off-by: Davide Caratti dcaratti@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/sch_fq_pie.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/net/sched/sch_fq_pie.c +++ b/net/sched/sch_fq_pie.c @@ -138,8 +138,15 @@ static int fq_pie_qdisc_enqueue(struct s
/* Classifies packet into corresponding flow */ idx = fq_pie_classify(skb, sch, &ret); - sel_flow = &q->flows[idx]; + if (idx == 0) { + if (ret & __NET_XMIT_BYPASS) + qdisc_qstats_drop(sch); + __qdisc_drop(skb, to_free); + return ret; + } + idx--;
+ sel_flow = &q->flows[idx]; /* Checks whether adding a new packet would exceed memory limit */ get_pie_cb(skb)->mem_usage = skb->truesize; memory_limited = q->memory_usage > q->memory_limit + skb->truesize;